The present invention relates to an improved inner periphery for a wrench wherein two protrusions are located between adjacent recesses in the inner periphery of the driving member.
A conventional driving member for driving but or bolt bead with hexagonal periphery generally includes a six surfaces and six concavities are located between the adjacent surfaces such that the six sides of the nut are matched with the six surfaces and can be rotated. However, there are two different systems for the specifications of the nuts, for example, a {fraction (11/16)} inch nut is slightly different from a 17-mm nut. There is 0.28 mm in difference for the two nuts so that when the driving member is used to tighten or loosen the two nuts, there will be a gap defined between the inner periphery of the driving member and the nut Several efforts are developed for overcoming the problems such as the disclosures shown in U.S. Pat. Nos. 4,765,211, 3,903,764, 5,388,486, and 5,219,392. Most of the efforts use a protrusion at a specific position of the inner periphery of the driving member so that the nuts with different specifications can be secured by the driving member. Nevertheless, the protrusion tends to be worn out because it protrudes along and bears a huge stress frequently. The tool has to be removed from the nut and turned to the other side to match the nut again when using the tool in opposite direction.
The present invention intends to provide a driving member that has an improved inner periphery to accommodate the nuts with different specifications.
In accordance with one aspect of the present invention, there is provided a driving member which includes a ring-shaped body having a hole defined therethrough and six concavities are defined equiangularly in an inner periphery of the ring-shaped body. Six engaging portions are located between the six concavities alternatively and each engaging portion includes a first engaging surface and a second engaging surface on two ends of the engaging portion.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.